Apparatus and method for scalable power distribution

ABSTRACT

In one aspect, the invention provides a system for power distribution. According to some embodiments, the system includes a rack mountable power distribution unit including a housing having a first end and a second end, the housing also including an outer wall defining a cavity within the housing, and fastening elements configured to allow the housing to be mounted within an electrical equipment rack. In accordance with these embodiments, the outer wall of the housing includes an opening extending linearly between the first end and the second end of the housing and a plurality of electrical conductors located within the cavity and oriented linearly between the first end and the second end. In accordance with further embodiments, the system includes a tap module.

RELATED APPLICATIONS

This application is a Continuation of U.S. patent application Ser. No.12/630,503, filed Dec. 3, 2009 which is hereby incorporated herein byreference in its entirety.

BACKGROUND OF INVENTION

1. Field of Invention

Embodiments of the invention relate generally to electrical powerdistribution equipment. More specifically, at least one embodimentrelates to an apparatus and a method for scalable power distribution.

2. Discussion of Related Art

Centralized data centers for computer, communications and otherelectronic equipment have been in use for a number of years. Morerecently, with the increasing use of the Internet, large scale datacenters that provide hosting services for Internet service providers(“ISPs”), application service providers (“ASPs”) and Internet contentproviders are becoming increasingly popular. Typical centralized datacenters contain numerous racks of equipment that require power, coolingand connections to communication facilities.

In general, centralized data centers have a power distribution systemconfigured to avoid power outages because the data centers include ahigh percentage of critical loads without which an enterprise may beunable to operate. Often, an uninterruptible power supply (“UPS”) isemployed in the power distribution system to ensure that equipmentreceives continuous power and avoids any power outages. Typical powerdistribution systems include racks of equipment, for example, serversand the like that are located in the data center. Generally, a pluralityof power distribution circuits are provided where each circuit suppliespower to one or more electrical loads (e.g., servers, cooling systems,lighting circuits, etc.) via a circuit breaker. These systems generallyinclude racks in which the circuit breakers are installed (i.e., powerdistribution units) or alternatively racks that include an electricalpanel board which is in general similar in design to the panel boardsthat are found in ordinary commercial facilities.

Problems with these approaches include the fact that the installation orremoval of a circuit breaker from the panel board or power distributionunit requires that a skilled individual (i.e., an electrician) performthe installation or removal in close proximity to energized electricalcircuits which may include exposed electrical connections and/orconductors. Alternatively, the power distribution equipment can bede-energized to facilitate the installation or removal of one or morecircuit breakers. Of course, given the critical nature of the electricalload in the data centers, even these scheduled outages are undesirable.

Some existing approaches attempt to minimize power interruptionsresulting from the connection of new power distribution circuits byproviding pre-fabricated plug-in power cables whereby a first end of thecable includes a connector that can be plugged into an output of acircuit breaker at the power distribution unit and a second end that canbe connected to an electrical load. Although this approach may allow anelectrical load to be safely connected to the circuit breaker withoutde-energizing the entire power distribution unit (e.g., connected withthe panel board energized but without requiring any “hot work”), itrequires that the cable lengths be pre-determined. In addition, suchsystems may not be scalable, that is, each panel board or other powerdistribution unit may not be configured for the correct size or quantityof circuits and corresponding circuit breakers.

SUMMARY OF INVENTION

In one or more embodiments, the invention provides a modular, scalablepower distribution system that provides tap modules that may be safelyinstalled and removed without disrupting other electrical circuitsconnected to the power distribution unit. As a result, in someembodiments, the invention provides for a scalable power distributionapparatus that provides flexibility to meet the changing electricalneeds of a facility such as a data center. For example, in someembodiments, a user can employ a rack mounted power distribution unit tocustomize the location of the connection for newly added load after theinitial installation and without disrupting the power supplied to anypreviously connected loads. In addition, the user can selectivelyconnect single-phase or three-phase loads to achieve a balanced currentdraw from a multi-phase source of electrical power. Further, in someembodiments, the preceding can be accomplished by user-selectableconnection of individual receptacle outlets to the power distributionsystem. In still another embodiment, the user-selectable connection isaccomplished without de-energizing any portion of the power system thatthe individual receptacle outlet is connected to.

In one aspect, the invention provides a system for power distribution.According to some embodiments, the system includes a rack mountablepower distribution unit including a housing having a first end and asecond end, the housing also including an outer wall defining a cavitywithin the housing, and fastening elements configured to allow thehousing to be mounted within an electrical equipment rack. In accordancewith these embodiments, the outer wall of the housing includes anopening extending linearly between the first end and the second end ofthe housing and a plurality of electrical conductors located within thecavity and oriented linearly between the first end and the second end.In accordance with further embodiments, the system includes a tap moduleincluding a plurality of contacts extending therefrom wherein each ofthe plurality of contacts is configured to be inserted into the openingbefore engaging one of the plurality of electrical conductors within thecavity, respectively.

In accordance with another aspect, the invention provides a tap moduleincluding a body; a shaft coupled to the body, the shaft including atleast a first region having a first diameter and a second region havinga second diameter which is different than the first diameter; and aplurality of contacts included in the shaft and extending therefrom, thecontacts including a phase-conductor contact, a neutral-conductorcontact and a ground-conductor contact. According to some embodiments,the phase-conductor contact is located in the first region, and one ofthe neutral-conductor contact and the ground-conductor contact islocated in the second region.

In accordance with yet another aspect, the invention provides a methodof providing power to a server, the method including acts of: mounting arack mounted power distribution unit in an electrical equipmentenclosure, the rack mounted power distribution unit configured toreceive a plurality of electrical modules at plurality of non-fixedlocations, respectively, along a length of the rack mounted powerdistribution unit; coupling an electrical module including an electricalcord at a location selected by a user from among the plurality ofnon-fixed locations; and connecting the electrical cord to the server.

BRIEF DESCRIPTION OF DRAWINGS

The accompanying drawings, are not intended to be drawn to scale. In thedrawings, each identical or nearly identical component that isillustrated in various figures is represented by a like numeral. Forpurposes of clarity, not every component may be labeled in everydrawing. In the drawings:

FIG. 1 illustrates a block diagram of an electrical system in whichscalable power distribution equipment is employed in accordance with oneembodiment of the invention;

FIG. 2 illustrates an isometric view of a plug-in module in accordancewith one embodiment of the invention;

FIG. 3 illustrates a plan view of a plug-in module in accordance withone embodiment of the invention;

FIG. 4 illustrates an isometric view of the plug-in module of FIG. 3 inaccordance with one embodiment of the invention;

FIG. 5 illustrates a plug-in module installed in a bus bar assembly inaccordance with one embodiment of the invention;

FIG. 6 illustrates a plug-in module in accordance with yet anotherembodiment of the invention;

FIG. 7 illustrates a block diagram of a bus bar assembly and plug-inmodules in accordance with an embodiment of the invention;

FIG. 8 illustrates a plug-in module in accordance with still anotherembodiment of the invention;

FIG. 9 illustrates a plug-in module in accordance with yet anotherembodiment of the invention;

FIG. 10 illustrates a plug-in module in accordance with still anotherembodiment of the invention;

FIG. 11 illustrates a power distribution unit in accordance with oneembodiment;

FIG. 12 illustrates a tap module in accordance with one embodiment;

FIG. 13 illustrates a plan view of a tap module in accordance with theembodiment of FIG. 12;

FIG. 14 illustrates a tap module connected to a power distribution unitin accordance with one embodiment; and

FIG. 15 illustrates a closer view of a connection of the tap module andthe power distribution unit in accordance with the embodimentillustrated in FIG. 14.

DETAILED DESCRIPTION

This invention is not limited in its application to the details ofconstruction and the arrangement of components set forth in thefollowing description or illustrated in the drawings. The invention iscapable of other embodiments and of being practiced or of being carriedout in various ways. Also, the phraseology and terminology used hereinis for the purpose of description and should not be regarded aslimiting. The use of “including,” “comprising,” or “having,”“containing”, “involving”, and variations thereof herein, is meant toencompass the items listed thereafter and equivalents thereof as well asadditional items.

Each of commonly-owned U.S. patent application Ser. No. 11/766,504,filed Jun. 21, 2007, entitled APPARATUS AND METHOD FOR SCALABLE POWERDISTRIBUTION and U.S. patent application Ser. No. 11/455,227, filed Jun.16, 2006, entitled APPARATUS AND METHOD FOR SCALABLE POWER DISTRIBUTIONdescribe embodiments of modular, scalable power distribution systemsthat provide flexibility to meet the changing electrical needs of afacility such as a data center, each of these applications isincorporated herein by reference in its entirety. The descriptionincluded herein provides further embodiments of apparatus and methodsfor scalable power distribution, for example, embodiments that allow auser to safely adapt the configuration of the power distribution systemto accommodate changing electrical loads and to do so withoutde-energizing the power distribution system.

FIG. 1 illustrates a power distribution system 10 in accordance with oneembodiment, where the system includes a power distribution unit 11(“PDU”) that provides a plurality of output circuits 18 (e.g., branchcircuits) to supply electrical power to a plurality of electrical loads,for example, loads found in a data center or another type of facility.The power distribution system 10 may include an input circuit breaker13, a transformer 14, an uninterruptible power supply (“UPS”) 15, abypass switch 16, a bus bar assembly 12 and monitoring and controlcircuitry 17. In various embodiments, the PDU 11 includes the bus barassembly 12 while each of the remaining apparatus listed in thepreceding sentence may either be included in the PDU 11, or optionally,be physically located elsewhere in the power distribution system 10.

According to one embodiment, the PDU 11 includes the bus bar assembly 12and each of the input circuit breaker 13, the transformer 14, the UPS15, the bypass switch 16 and the monitoring and control circuitry 17, asillustrated in FIG. 1. In another embodiment, each of the input circuitbreaker 13, the transformer 14, the UPS 15, the bypass switch 16 and atleast a part of the monitoring and control circuitry 17 are locatedexternal to the PDU 11. In other embodiments, various combinations ofthe input circuit breaker 13, the transformer 14, the UPS 15, the bypassswitch 16 and the monitoring and control circuitry 17 are co-locatedwith the bus bar assembly 12 in the PDU 11. Thus, in one embodiment, thebus bar assembly 12, the input circuit breaker 13, the transformer 14,the bypass switch 16 and at least a part of the monitoring and controlcircuitry 17 are located in the PDU 11 while the UPS is located externalto the unit 11. In yet another embodiment, the power distribution system10 does not include a UPS. As a result, in one embodiment, the PDU 11includes the bus bar assembly 12 and each of the input circuit breaker13, the transformer 14, and at least a part of the monitoring andcontrol circuitry 17, while the UPS 15 and the bypass switch 16 are notemployed with the PDU 11.

According to one embodiment, the PDU 11 is contained within an equipmentrack that allows the “rack mounting” of the bus bar assembly 12 andothers of the apparatus included within it. In a version of thisembodiment, the PDU 11 is included in a row of equipment racks that maybe coupled to one another as is well known to those of ordinary skill inthe art. As a result, in some embodiments, the PDU 11 includes the busbar assembly 12, while one or more other equipment racks include othersof the input circuit breaker 13, the transformer 14, the UPS 15, thebypass switch 16 and the monitoring and control circuitry 17. Inversions of these embodiments, the equipment racks including theapparatus identified here are coupled together to form a row ofequipment racks employed in the power distribution system 10, forexample, as described in commonly assigned U.S. Pat. No. 6,967,283,entitled “Adjustable Scalable Rack Power System and Method,” issued Nov.22, 2005 to Neil Rasmussen et al. which is incorporated by referenceherein. The above-described configurations describe only some of thepossible configurations and are not intended to be limiting.

In accordance with one embodiment, the bus bar assembly 12 is adapted toreceive at least one plug-in module that may include a switching deviceand overcurrent protection (e.g., an electrical isolation andovercurrent protection device), for example, a circuit breaker, a fusedswitch, or a separate switch and one or more fuses. In one embodiment,the plug-in module is installed in the bus bar assembly 12 to connectthe bus bar assembly to the output circuits. As is described in greaterdetail below, in various embodiments, the plug-in module may include apre-terminated power cable to facilitate a safe connection of new outputcircuits with the PDU 11 and the bus bar assembly energized. Further, invarious embodiments, the bus bar assembly 12 provides a region free ofuninsulated conductors in which the plug-in module is installed.

In one embodiment, the bus bar assembly 12 includes a plurality ofpositions A-H that are each adapted to receive a plug-in module. In aversion of this embodiment, the bus bar assembly is rated for a maximumcontinuous current of 400 Amps while each position A-H is rated for amaximum continuous current of 100 Amps. In one embodiment, each of theplug-in modules is also rated for 100 Amps although various ampacitycircuit breakers may be included in the plug-in modules, e.g., havingampacities of from less than 1 Amp up to and including a maximum of 100Amps. Such an approach may, in various embodiments, provide a scalablesystem that can employ two elements (i.e., a bus bar assembly andplug-in modules) to meet a wide variety of the existing and futureelectrical needs of a facility. This results in efficiencies inmanufacturing, supply chain and operation and maintenance for theequipment. For example, a manufacturer need not manufacture and adesigner need not try to select from a plurality of semi-customequipment. Accordingly, the equipment may have a lower cost and greateravailability.

As illustrated in FIG. 1, a source of input power is connected to theline side of the input circuit breaker 13, the load side of the inputcircuit breaker 13 is connected to a line side (i.e., the input) of thetransformer 14, the load side (i.e., the output) of the transformer 14is connected to the input of the bypass switch 16, and the output of thebypass switch 16 is connected to the bus bar assembly 12. In oneembodiment, both the input and the output of the UPS 15 are connected tothe bypass switch 16. As is well known by those of ordinary skill in theart, the bypass switch 16 operates to selectively connect the output ofthe bypass switch 16 to either the transformer 14 or the UPS 15. Inaccordance with one embodiment, the bus bar assembly 12 receives thepower from the bypass switch 16 and supplies power to one or more outputcircuits 18. In one embodiment, the bypass switch is adapted toselectively couple the output of the transformer 14 and the output ofthe UPS 15 to the bus bar assembly 12.

The monitoring and control circuitry 17 may perform solely monitoringfunctions, solely control functions or a combination of monitoring andcontrol. In various embodiments, monitoring includes any one or anycombination of the following functions and/or the following functionsand additional functions: current sensing, power monitoring (e.g.,energy consumption), circuit on/off sensing, bypass switch status, UPSstatus and the like. Any of the preceding may be accompanied by signalprocessing employed for the purpose of monitoring and/or control. Forexample, current and voltage signals may be processed to determineenergy consumption. Accordingly, the monitoring and control circuitry 17may include one or more processors, e.g., microprocessors.

In addition, the monitoring and control circuitry 17 may includecommunications with any of the various components included in the PDU11. Accordingly, in some embodiments, the PDU includes circuitry (notshown) that connects the monitoring and control circuitry 17 to one ormore of the bus bar assembly 12, input circuit breaker 13, thetransformer 14, the UPS 15, and the bypass switch 16. Further, invarious embodiments, the monitoring and control circuitry 17 may beincluded in or communicate with a local area network and or a wide areanetwork (e.g., the Internet).

In further embodiments, control functions include any one or anycombination of the following functions and/or the following functionsand/or additional functions: control of UPS operation, control of bypassswitch operation, operation of one or more circuit breakers, otherswitching operations and the like. Accordingly, the monitoring andcontrol circuitry 17 may include a user interface such as a displayand/or switches, meters, indicating lights, and the like.

Referring now to FIG. 2, an isometric view of a plug-in module 20 inaccordance with one embodiment of the invention is illustrated. Ingeneral, the plug-in module 20 is employed to supply power from the PDU11 to an electrical load. Further, in accordance with variousembodiments of the invention, the plug-in module 20 includes a switchingdevice such that a line-side of the plug-in module connects to a sourceof electrical power and a load side of the plug-in module 20 can bedirectly connected to an electrical load or connected to furthercircuitry that is connected to the electrical load. Thus, in oneembodiment, the plug-in module 20 includes a circuit breaker that canprovide electrical isolation and overcurrent protection (e.g., aminiature molded case circuit breaker that senses overloads and/or shortcircuits). In other embodiments, the plug-in module includes acombination of an isolation switch and fusing such as a fused disconnectswitch or a combination of a switch and fuses that are separate from oneanother. In accordance with one embodiment, the plug-in module is sizedand adapted for installation in a bus bar assembly, for example, the busbar assembly 42 illustrated in FIG. 5. In various embodiments, theplug-in module 20 includes a power cable 21 which may include an endthat is pre-terminated at the plug-in module 20.

As used herein, the term “pre-termination” refers to the fact that afirst end of the power cable 21 is connected at the plug-in module 20before the plug-in module arrives on a job site. According to oneembodiment, the pre-termination is performed during the manufacture ofthe plug-in module 20.

In some embodiments, the length of the power cable 21 is alsoestablished during manufacture. That is, in one embodiment, a pluralityof commonly used fixed lengths of power cable 21 may be available. In aversion of this embodiment, the plurality of commonly used fixed lengthsare established based on a distance between a first enclosure and/orequipment rack and a second enclosure and/or equipment rack. Thus, aconnection between the plug-in module 20 and an immediately adjacentequipment rack may require a shorter length of cable when compared withthe length of cable required for a connection between the plug-in module20 and a more distant equipment rack. Because equipment racks are oftensupplied in standard sizes the length of the power cables 21 can bedetermined in advance. In addition, a second end of the power cable 21may include a connector to facilitate the connection of the power cable21 to an electrical load.

As illustrated in FIG. 2, the plug-in module 20 includes a housing 22having a top panel 23, a front panel 24 and a first side panel 26. Invarious embodiments, the plug-in module 20 may also include a bottompanel, a rear panel and a second side panel (located opposite the first)which are not illustrated in FIG. 2. The housing 22 may be manufacturedusing any rigid material (conductive material or insulating material)suitable for use with electrical equipment, for example, the housing maybe manufactured from steel. In some embodiments, portions of the housingare conductive while other portions of the housing are insulating.According to one embodiment, a first extension 28 extends from the firstside panel 26 in a substantially perpendicular direction while a secondextension 30 may extend from the second side panel.

In various embodiments, the plug-in module 20 may include additionalfeatures and various combinations of features. For example, according toone embodiment, the plug-in module 20 includes a handle 32 that isattached to the housing 22 (e.g., at the front panel 24) which may beemployed by a user to install and remove the plug-in module 20. In someembodiments, the plug-in module 20 includes a latch 33 that secures theplug-in module 20 in a fully installed position. In the illustratedembodiment, the latch 33 is attached to an end of the first extension28. Alternatively, a single latch 33 may be attached to an end of thesecond extension 30. In yet another embodiment, a separate latch 33 maybe attached to each of the first extension 28 and the second extension30.

In addition, one or more of the housing 22 and/or extensions 28, 30 mayinclude a rejection feature to provide an interference employed toprevent the installation of a plug-in module 20 based on one or moreconditions, for example, where a nominal voltage rating of the plug-inmodule 20 is lower than a nominal voltage rating of equipment (e.g., thebus bar assembly) in which the plug-in module is being installed, wherethe plug-in module is being installed up-side down, etc.

The plug-in module 20 may also include a guide element 36 which mayassist in properly aligning the plug-in module 20 when it is beinginstalled. For example, the guide element 36 may engage a correspondingpart of an enclosure/rack or bus bar assembly in which the plug-inmodule 20 is being installed. The guide element 36 may be an integralpart of the housing or a separate component. In addition, a plurality ofguide elements 36 may be employed. In one embodiment, the guide element36 is a rail located on the side panel 26 of the housing 22. In thisembodiment, the guide element 36 may engage a corresponding groove in,for example, a bus bar assembly. In a further embodiment, a separateguide element 36 is included on each of the side panels. It should beapparent to those of ordinary skill in the art that the guide element orelements 26 may include structure other than a rail, for example, a tabor an extension (such as a cylindrical extension) may be employed.Further, the guide element may be located anywhere on the plug-in module20 that will facilitate a proper alignment of the module. It should alsobe apparent that the guide element 36 need not extend from the plug-inmodule but may instead be a groove, channel, tube, hollow or otherrecess that engages corresponding structure extending from the bus barassembly, enclosure and/or rack in which the plug-in module 20 isinstalled.

The latch 33 may include a variety of different structure that allowsthe plug-in module 20 to be retained in a fully-installed position,e.g., with the plug-in module 20 fully connected to the bus bar assembly42. For example, the latch 33 may have a range of motion such that thelatch 33 deflects from an at-rest position as the plug-in module 20 isinstalled and then captures (or is captured by) a part of the bus barassembly and/or rack in which it is installed. As should be apparent toone of ordinary skill in the art, the latch 33 can be manufactured fromflexible material and/or rigid material configured to flex in an elasticmanner when pressure is applied to the latch 33.

As mentioned above, the plug-in module 20 may include a circuit breaker34 such that the plug-in module 20 can provide overcurrent protectionfor the electrical load to which it is connected, e.g., it can provideoverload and short circuit protection. In one embodiment, the circuitbreaker 34 is located such that at least a part of the circuit breakeris accessible with the housing 22 completely assembled. For example, thefront panel 24 may include an opening through which the face of thecircuit breaker 34 is accessible and/or extends. Such a configurationcan allow the circuit breaker status (i.e., open, closed, tripped, etc.)to be determined and also allow operating personnel to operate thecircuit breaker 34.

In one embodiment, the circuit breaker 34 is a Pro-M series miniaturecircuit breaker manufactured by ABB. Example part numbers for IEC ratedcircuit breakers include: S201-K16; S201-K32; S203-K16; and S203-K32.Example part numbers for circuit breakers designed to meet traditionalU.S. standards include: S201U-K20; S203U-K32; and S203U-K50. In anotherembodiment, the circuit breaker 34 is a L-Series miniature circuitbreaker manufactured by Altech. Examples include a Catalog No. 1 CU02Lrated for 0.2 Amps and single pole applications and a Catalog No. 3CU63Lrated for 63 Amps and three pole applications. It should be apparent tothose of ordinary skill in the art that other makes, models andconfigurations (e.g., four pole, six pole, etc.) can be employed. Inaddition, the plug-in module 20 can include a circuit breaker thatcomplies with any applicable standard from any of a variety of standardsetting bodies.

As illustrated, the power cable 21 is pre-terminated within the housing22, however, in an alternate embodiment the power cable 21 ispre-terminated external to the housing 22. Further, where the powercable 21 is pre-terminated to the plug-in module 20, the pre-terminationprovides a connection between one or more of the conductors included inthe power cable 21 and the circuit breaker 34. In accordance with oneembodiment, the pre-termination results in the power cable 21 beingdirectly connected to one or more terminals/lugs integral with thecircuit breaker 34. However, such a direct connection is not requiredand various other configurations may be employed. For example, the powercable 21 may be terminated at another terminal point/lug located in theplug-in module 20. In this embodiment, a jumper or short piece of cable,wire, etc. may connect the terminal point/lug (and as a result the powercable) to the circuit breaker 21.

The plug-in module 20 may also include various control elements toprovide status indications and/or allow control of, for example, thecircuit breaker 34. According to one embodiment, the plug-in module 20includes one or more status indication lights that may be located in thefront panel 24 and used to indicate a circuit breaker status. In anotherembodiment, the plug-in module 20 may include a relay that can beemployed to open the circuit breaker to disconnect the load beingsupplied by the plug-in module 20 as part of a load shedding scheme. Inaddition, the circuit breaker or other isolating means may beelectrically operated such that is can be electrically opened, closedand reset. The plug-in module 20 may also include an auxiliary switch orone or more voltage sensors to determine the position of the poles ofthe circuit breaker, the status of switch contacts or the status offuses.

Further, the plug-in module 20 may also include one or more temperaturesensors to provide data concerning, for example, the temperature ofcontacts that connect the plug-in module 20 to the bus bar assembly 12,the temperature of circuit breaker and/or the temperature of the circuitbreaker terminals/lugs. In some embodiments, the preceding approach maybe employed to reduce or eliminate the need to perform IR scanning forover temperature conditions. In one embodiment, the preceding approachprovides data that is employed to supplement IR scanning, for example,to identify areas of interest.

FIG. 3 illustrates a plan view of the plug-in module 20 of FIG. 2 withthe top of the housing (e.g., a top panel) removed. A second side panel27 and a rear panel 40 included as part of the housing 22 areillustrated in FIG. 3. In addition to the housing 22, the power cable 21and the circuit breaker 34, e.g., a molded case circuit breaker, theplug-in module 20 includes line conductors 52, a neutral conductor 54, aground conductor 56 and a plurality of contacts 58. In accordance withone embodiment, the power cable 21 includes each of the line conductors52, the neutral conductor 54, and the ground conductor 56. In oneembodiment, additional line conductors 59 connect the circuit breaker 34to the contacts 58. Further, in one embodiment, each line conductor 59is ultrasonically welded to the corresponding contact of the pluralityof contacts 58. As should be apparent to those of ordinary skill in theart, other configurations of the power cable may be employed, forexample, the power cable 21 may not include a neutral when the plug-inmodule 20 is connected to a 3-wire load. As illustrated in FIG. 3, insome embodiments, the power cable 21 may have the line conductors 52pre-terminated at the circuit breaker while the neutral conductor 54 andthe ground conductor 56 are terminated elsewhere in the plug-in module20.

In accordance with one embodiment, the plug-in module 20 includes amechanical stress relief device 57 for the power cable 21. That is, theplug-in module 20 includes a device to reduce any forces that may tendto pull the pre-terminated power cable 21 from the plug-in module 20.According to one embodiment, the mechanical stress relief device 57includes an internal bushing, an external bushing, other hardware, or acombination of any of the preceding. In one embodiment, the mechanicalstress relief device 57 is a type of stress relief device that is alsosuitable for use with twist lock cord end connectors. In a version ofthis embodiment, the mechanical stress relief 57 is a strain reliefdevice provided by Hubbell Incorporated, for example, a model that isapproved by Underwriter's Laboratory. According to one embodiment, themechanical stress relief 57 is overmolded onto the power cable 21 wherethe power cable 21 includes three single phase power cords.

In addition, in one embodiment, the plurality of contacts 58 are locatedoutside the housing proximate the rear panel 40. In one embodiment, eachof the electrical contacts include a pair of contact “fingers” sized andadapted to engage a bus bar with a proper amount of tension to create astable electrical connection when the plug-in module 20 is inserted inthe bus bar assembly 42, e.g., the contacts provide sufficient pressureto prevent the connection with the bus bar from overheating when currentis being carried by the plug-in module. As should be apparent, otherconfigurations of the plurality of contacts 58 may be employed so longas the contacts 58 are adapted to removably engage correspondingstationary contacts and/or contact surfaces. Stationary conductors,stationary contacts and stationary contact surfaces have fixed positionsthat cannot be moved when the PDU is in service, i.e., when the PDU isenergized. In the illustrated examples, a bus bar can be a stationaryconductor that provides a stationary contact surface. In a version ofthis embodiment, the neutral conductor 54 and the ground conductor 56are pre-terminated at the corresponding contacts 58, respectively.According to one embodiment, the contacts 58 are manufactured fromcopper with a 2-3 micron coating of nickel and a tin plating finish. Ina further embodiment, contact pressure is assisted by a spring clip, forexample, a spring clip manufactured from carbon steel or stainlesssteel.

In one embodiment, the plug-in module 20 also includes a plurality ofcurrent sensing devices 62, for example, current transformers (“CTs”).According to one embodiment, the plug-in module 20 includes a separatecurrent sensing device 62 for each line conductor. Thus, according toone embodiment, the plug-in module 20 is employed with a three phasecircuit and includes three CTs. Of course, other configurations may beused, for example, the plug-in module may also include a fourth CT forsensing neutral current. A wide variety of current sensing devices maybe employed provided that they include a suitable current rating andphysical dimensions that allow them to be installed within the housing22 of the plug-in module 20. Example current sensors include: a part no.5304 from Amecon Inc.; a part no. T75001 from Falco Electronics, LTD.;and a part no. 460-1001 A from Shilchar-payton Technologies, LTD.

In accordance with one embodiment, the plug-in module 20 includes aconnector 64 sized and adapted for connecting one or more secondarycircuits to circuitry located external to the plug-in module 20 when theplug-in module is installed in the bus bar assembly 42. Secondarycircuits can include any monitoring and/or control circuits includingcircuits that employ the output of the current sensors. Accordingly, theconnector 64 may be employed to connect secondary circuits or portionsthereof included in the plug-in module 20 to secondary circuitryincluded in the monitoring and control circuitry 17.

In various embodiments, the connector 64 includes at least one contactwhich is configured to engage a corresponding contact (not shown)included in the bus bar assembly. As should be apparent to those ofordinary skill in the art, that various styles and types of contacts maybe employed provided that the contacts and connector are rated for thenominal operating voltage and nominal current of the secondary circuitor circuits. According to one embodiment, the connector 64 extends fromwithin the housing 22 through the rear panel 40. In one embodiment, theconnector 64 is adapted to mate with an edge connector included in thebus bar assembly 42. Example connectors include: a part no. 5-5530843-0from Tyco Electronics Corp.; and a part no. 2551-20D from Ito-ChienEnterprise Co. Ltd.

In accordance with one embodiment, a part 65 of the circuit breaker 34externally accessible (i.e., accessible outside the housing 22) isillustrated. In addition, FIG. 3 illustrates the use of the guideelement 36 (i.e., a first guide element) and a second guide element 37.

Referring now to FIG. 4, an isometric view of the plug-in module of FIG.3 is illustrated. As illustrated here, each of the three current sensors62 is clearly shown. In accordance with one embodiment, the currentsensors 62 are included on a printed circuit board (“PCB”) 66 locatedwithin the housing 22. In addition, the portion of the connector 64located within the housing 22 is illustrated. In accordance with oneembodiment, the connector 64 is also coupled to the PCB 66 within thehousing. In a version of this embodiment, at least some of the contactswithin the connector 64 are connected to circuitry located on the PCB66.

In some embodiments, the secondary circuitry located in the plug-inmodule 20 does not include a processor or any control functions, forexample, the secondary circuitry may simply provide the output of thesensing devices to the connector 64. The outputs may then becommunicated to the monitoring and control circuitry 17 via theconnector 64 when the plug-in module is installed in the bus barassembly 42. In alternate embodiments, the secondary circuitry includesa processor 68 (e.g., a microprosessor), for example, located on the PCB66. In versions of these embodiments, the processor 68 may be employedto perform either monitoring, control functions or both. Further, theprocessor 68 can be included in the monitoring and control circuitry 17when the plug-in module is installed in the PDU 11.

In one embodiment, the plug-in module 20 includes a memory 69 (e.g.,RAM, ROM, etc.) that stores information, for example, informationconcerning the plug-in module 20. The information may include theampacity of the plug-in module 20, the quantity of poles, the date ofmanufacture, the manufacturing facility, authenticity codes, the size ofthe conductors included in the power cable 21, the style of the powercable 21, the length of the power cable 21 and other information.According to one embodiment, the plug-in module 20 is programmed withthe preceding information at the time of manufacture. Further, where theplug-in module 20 communicates with a communication network (forexample, via the connector 64) the information can be employed toautomatically set up and provide information concerning the plug-inmodule 20 to a power distribution monitoring system. In one embodiment,the memory 69 is included in a chip, for example, an EPROM chip.

As mentioned previously, the plug-in module may be installed in a busbar assembly, for example, the bus bar assembly 12 located in PDU 11.Referring now to FIG. 5, a system 40 is shown in which the plug-inmodule 20 is installed in a bus bar assembly 42 at a first position,i.e. position D. In accordance with the illustrated embodiment, the busbar assembly includes a plurality of positions in which separate plug-inmodules may be installed. In the interest of clarity, only 5 of theavailable positions are uniquely identified, positions A, B, C, D, andE, with position E being the position immediately below the position inwhich the plug-in module 20 is installed, position C being above andimmediately adjacent position D and each of positions A and B beinglocated further above position D.

In one embodiment, the bus bar assembly 42 includes a plurality of busbars 43 and the plug-in module 20 is installed by sliding the moduleinto the bus bar assembly 42 to engage electrical contacts 58 at therear of the plug-in module 20 with the bus bars 43. In one embodiment,bus bar assembly includes a first side panel 44 and a second side panel45. The side panels 44, 45 may each be a single unit, or alternatively,may each include a plurality of side panels. For example, the sidepanels 44, 45 may include a separate side panel for each of theplurality of positions, e.g., the positions A-E. The side panels 44, 45may be manufactured using any rigid material (conductive material orinsulating material) suitable for use with electrical equipment, forexample, the side panels 44, 45 may be manufactured from steel. Inanother embodiment, the side panels 44, 45 are manufactured frominsulating material. Either or both of the side panels 44, 45 mayinclude a guide element 46 that is used to properly position and guidethe plug-in module 20 as it is installed.

The bus bar assembly 42 may also include a rear panel 48 that providesan electrically insulating barrier between the region where the plug-inmodule(s) are located and the location of the bus bars 43. In oneembodiment, the rear panel 48 is made of plastic. In accordance with oneembodiment, the rear panel 48 includes a plurality of openings 50 thatare sized and adapted to allow the electrical connection to be made withthe plug-in module 20 but are small enough to prevent the accidentalcontact of a user and/or hand tools with the bus bar.

In some embodiments, the rear panel 48 includes a connector 68 that canbe employed to connect the monitoring and control circuitry 17, or aportion thereof, to secondary circuitry included in the plug-in module20.

The plug-in module 20 may include single pole circuit breakers or multipole circuit breakers in various embodiments. In some embodiments, thecircuit breaker is a three pole circuit breaker while in otherembodiments, the circuit breaker is a six pole circuit breaker.

The power cable 21 may also include a variety of embodiments dependingupon the load that is being supplied by the plug-in module 20. Forexample, the plug-in module 20 may supply either a single phase load,multiple single phase loads or three phase load. In addition, the secondend of the power cable 21 (i.e., the end that is not pre-terminated) mayinclude a connector.

FIG. 6 illustrates an embodiment where a plug-in module 20 includes apower cable 21 that is split into a plurality of branch cables 21A, 21B,and 21C. In one embodiment, the plug-in module 20 is a three phasemodule and the power cable 21 includes conductors for all three phases.Each of the three phases may be split into branch cables 21A, 21B and21C, one phase per branch cable. In a further embodiment, however, threesingle pole circuit breakers (e.g., three circuit breakers 34) areincluded in the plug-in module and the power cable 21 is split into thethree branch cables where the first branch cable 21A includes a singlephase supplied by one single pole breaker, the second branch cable 21Bincludes another single phase supplied by another single pole breaker,and the third branch cable 21C includes the remaining single phasesupplied by the third single pole breaker. The immediately precedingapproach can save space by allowing three separate branch circuits to besupplied via a single plug-in module.

In one embodiment, each of the three branch cables 21A, 21B, 21Cincludes a connector 78 that can be plugged into an equipment rack. Inanother version, the power cable includes a three phase connector. Anyof a variety of connectors may be employed including NEMA L21-20, L5,L6, L14, and L15 connectors, type CS50 connectors, IEC309 pin and sleevedevices, etc.

The preceding architecture may be employed to supply equipment racksthat are adjacent a PDU in which the plug-in module 20 is installed. Inone embodiment, the power cable 21 is connected to a three phaseequipment rack (i.e., a rack that includes three phase load). In anotherembodiment, the first branch cable 21A is connected to a first equipmentrack, the second branch cable 21B is connected to a second equipmentrack, and the third branch cable 21C is connected to a third equipmentrack where each of the first, second and third equipment racks aresingle phase equipment racks (i.e., racks that only require single phasepower.)

Further, the power cable 21 may be supplied in fixed lengths that areestablished when the equipment is ordered, for example, where thedimensions of a plurality of equipment racks with which the plug-inmodule 20 is employed are known, a pre-determined length may beaccurately determined for the power cable 21 that is to connect theplug-in module 20 to equipment in another rack.

FIG. 7 illustrates an embodiment that employs a plurality of adjacentequipment racks including a first rack 74A which includes a bus barassembly 42 and plug-in modules 20. One or more additional equipmentracks are also included, i.e., a second rack 74B, a third rack 74C and afourth rack 74D. According to one embodiment, one or more of the racks74B, 74C and 74D include electrical load that is supplied power via theplug-in module 20. In a further embodiment, the first rack 74A includesa UPS that supplies power to the bus bar assembly 42. As a result, theload supplied via each of the plug-in modules 20 is also supplied powerfrom the UPS.

In accordance with one embodiment, the plug-in modules 20 includepre-terminated power cables 21 which may each include a connector 78.For example, the equipment racks 74B, 74C and 74D may each includesingle phase load that are connected to the plug-in modules 20 via thecables 21A, 21B and 21C, respectively. Alternatively, or in combinationwith the preceding, one or more of the cables 21A, 21B and 21C maysupply polyphase power (e.g., three phases) to one or more of theequipment racks 74B, 74C and 74D.

Each of connectors 78A, 78B and 78C may connect the power cable 21 to apower cable 80A, 80B, and 80C associated with one of the equipment racks74B, 74C and 74D, respectively. Thus, in some embodiments, the powercables 80A, 80B and 80C complete the electrical connection between theplug-in modules 20 and the equipment rack that is receiving power fromthe plug-in modules 20. In addition, the connectors 78A, 78B and 78C maybe connected to a corresponding connector (not illustrated) attached tothe end of the power cables 80A, 80B and 80C.

FIG. 7 illustrates one example of a power distribution systemarchitecture employing the bus bar assembly 42 and plug-in modules 20,however, various embodiments of the invention support otherconfigurations. Additional equipment, for example, UPS batteries may beincluded in the equipment rack 74A. In some embodiments, the powercables 21 may be connected to remote equipment racks. Further, theremote equipment racks may include an additional bus bar assembly andplug-in modules. That is, in one embodiment, a plug-in module in a firstbus bar assembly may supply power to a second bus bar assembly. Inanother embodiment, a bus bar assembly and plug-in modules may belocated in an equipment rack where all the electrical load that issupplied power by the plug-in modules is located in one or more remoteequipment racks. Other combinations of the above configurations andcombinations of the above and different configurations may also beemployed.

In various embodiments, one or more receptacle outlets may be includedat the second end of the power cable. A receptacle outlet provides for adirect connection to power utilization equipment such as rack mountedequipment (e.g. switches, routers, hubs, patch panels, servers andserver equipment racks/blade server chassis), desktop computers,printers, HVAC equipment, motors, etc. In an embodiment, this directconnection is established by physically mating a receptacle outlet to anattachment plug of the power utilization equipment. As is discussedfurther below, receptacle outlets may conform to various standards forsize, shape, pin-count, voltage, amperage, and phase. Further thereceptacle outlets may be configured in a “female” configuration (asillustrated herein) or in a “male” configuration so long as thereceptacle outlet is configured to connect to a corresponding connectorof the power utilization equipment.

Each of the embodiments described with regard to FIGS. 15-17 below maybe installed using a similar technique. In this technique, the plug-inmodule 20 is connected to the power distribution system and the powercable 21 may be installed by running the cable 21 through an overheadcable management system. Further, the one or more receptacle outlets maybe feed into an equipment rack and attached to it or the equipment ithouses by using keyhole connectors, magnets, VELCRO® Brand hook and loopfasteners or other fastening hardware. The one or more receptacleoutlets may include a flange to facilitate this attachment. Using theplug-in module 20 in this fashion may decrease the rack space requiredby the power distribution system. Furthermore, providing for factoryassembled plug-in modules connected to one or more receptacle outletsmay decrease the need for field wiring and thus decrease downtime and/orrequired hot work.

For example, FIG. 8 illustrates an embodiment where a plug-in module 20includes a power cable 21 that is connected to a rack mountable powerdistribution unit (“RMPDU”) 1500, e.g. a “power strip” includingfastening hardware/structure that allows the power strip to be securedin an equipment rack, which may include multiple receptacle outlets. Ascan be seen in FIG. 8, the plug-in module 20 connects to the power cable21 and the power cable 21 connects to the RMPDU 1500. The plug-in module20, the power cable 21 and the RMPDU 1500 may support single phase orthree phase power distribution. The RMPDU 1500 may include one or moreoutlets.

In various embodiments, power utilization equipment, such as rackmountable equipment, may be plugged directly into the RMPDU 1500. Inthis example, the RMPDU 1500 may include any receptacle outlet orcombination of receptacle outlets including IEC 320 C13, C19 and NEMAL6-20, among other styles and types of IEC and NEMA connectors. Thereceptacle outlets may have various voltage ratings such as, forexample, 120V, 240V and/or 415V and various amperage ratings such as,for example, 12 A, 15 A, 16 A, 24 A and/or 32 A. Further, the receptacleoutlets may provide connections configured for a single phase or amulti-phase (e.g. three phase) circuit. Embodiments of the precedingapproach to distributing power to rack mounted equipment may result in areduced number of connections, reduce the space required for the powerdistribution system and reduce the need for field wiring. In addition,the resulting installation may be completed at a lower cost with ahigher degree of safety.

In one embodiment, the RMPDU may include indicia adjacent to thereceptacle outlet(s) to indicate the ampacity of the outlet and/or thelines (e.g., phases) of a multi-phase power source that are connected tothe outlet. Further, groups of multiple receptacle outlets may beassociated with a first common connection L1-L2, while another group ofreceptacle outlets in the same RMPDU may be associated with a secondcommon connection L2-L3. In one version, indicia associated with eachgroup, respectively, which appears on the RMPDU provides informationconcerning the line connections.

The RMPDU 1500 may include a display, not shown, that providesinformation regarding the plug-in module 20. For example, where theplug-in module supports three phase power distribution, the display mayprovide information regarding the amount of load being supplied by eachof the phases, for example, information provided by one or more currentsensors. This information can be used, for example, to balance the loadacross the three phases when connecting power utilization equipment.That is, in one embodiment, a display, e.g., a display integral to theRMPDU, is used to monitor the load on a plurality of phases connected tothe RMPDU, as each piece of utilization equipment is connected to theRMPDU. The user may select one of a plurality of receptacle outletsincluded in the RMPDU to which additional power utilization equipmentshould be connected based on the loading, e.g. the current draw, of eachphase included in the RMPDU. In one embodiment, the user employs theindicia when selecting the receptacle outlet.

In another embodiment, a mobile computing device may provide informationconcerning the plug-in module 20. For example, scannable identification(such as IR-scannable identification, e.g., bar code labels, etc.) maybe affixed to the plug-in module 20 and/or RMPDU in which the plug-inmodule is installed (or will be installed). According to one embodiment,the mobile computing device can be used to scan the identification andthen, based on the identification information, provide a user of thecomputing device with the loading of the plug-in module 20 and/or RMPDUon a per-phase basis. In one version, the user can then determine whereto connect additional load based on this information. In anotherversion, the mobile computing device may use this information toidentify and recommend to the user specific rack and/or receptacleoutlet connections that should be used to supply additional powerutilization equipment. For example, to maintain a substantially balancedloading, the mobile computing device may use an amount of load beingsupplied by each phase of the RMPDU to determine the receptacle outletto which additional power utilization equipment should be connected.

FIG. 9 illustrates another embodiment in which the power cable 21 maysupply one or multiple receptacle outlets. The depicted embodimentincludes a housing 1600 and a plurality of receptacle outlets 1604A,1604B and 1604C. An end of a power cable 21, is connected to theplurality of receptacle outlets 1604A, 1604B and 1604C within thehousing 1600. In accordance with one embodiment, a second end of thepower cable is connected to a plug-in module.

In one embodiment, receptacle outlets 1604A, 1604B and 1604C,respectively, are located in separate receptacle outlet cavities (notshown) in the housing 1600. In the illustrated embodiment, the housing1600 includes flange 1602, which may be used to prevent unwantedmovement of the housing after installation, so that a positiveelectrical connection of the receptacle outlets and correspondingutilization equipment may be maintained. That is, in accordance with oneembodiment, a fastener may be inserted through a hole in the flange 1602and secured to the power utilization equipment, or component thereof.

Further, the embodiment illustrated in FIG. 9 may allow rack space to beconserved. For example, the receptacle outlet cavities may be spaced toalign with corresponding attachment plugs of the power utilizationequipment. This embodiment may be used to directly connect and supplypower to one or more server equipment racks, such as a blade serverchassis, via the receptacle outlets 1604A, 1604B, 1604C, i.e. withoutthe need for additional cabling. Thus, in some embodiments, the plug-inmodule 20 may be coupled to a set of receptacle outlets configured for aspecific application. Further, various embodiments, may also provide foran uninterrupted electrical connection from the plug-in module to thepower utilization equipment while greatly reducing the amount andcomplexity of any field wiring. In various embodiments, the housing 1600encloses the termination and/or connections of the cable 21 to therespective outlet receptacles 1604A, 1604B and 1604C.

FIG. 10 illustrates an embodiment where a plug-in module 20 includes apower cable 21, a junction 1700 and separate cables 1704A, 1704B and1704C each connected to separate receptacle outlets 1702A, 1702B and1702C, respectively. As shown in FIG. 10, the plug-in module 20 connectsto the power cable 21 which includes the junction 1700. In accordancewith one embodiment, the junction 1700 is a location of the power cable21 at which the power cable is split into the separate cables 1704A,1704B and 1704C, respectively. In the illustrated embodiment, separatereceptacles outlets 1702A, 1702B and 1702C are located at the end of theseparate cables 1704A, 1704B and 1704C, respectively. Thus, inaccordance with one embodiment, the power cable 21 includes a first endconnected to an overcurrent protection device, and a second end, a thirdend, and a fourth end at which the receptacle outlets 1702A, 1702B and1702C are located, respectively. In various embodiments, the plug-inmodule 20 illustrated in FIG. 10 may support single phase or multi-phasepower distribution.

In a further embodiment, power utilization equipment, including rackmounted equipment, may be plugged directly into the receptacle outlets1702A, 1702B and 1702C. In this example, the receptacle outlets 1702A,1702B and 1702C may include any receptacle outlet including IEC 320 C13,C19 and NEMA L6-20, among other IEC and NEMA connectors. The receptacleoutlets may have various circuit voltage ratings such as, for example,120V, 240V and/or 415V and various circuit amperage ratings such as, forexample, 12 A, 15 A, 16 A, 24 A and/or 32 A. Further, the receptacleoutlets 1702A, 1702B and 1702C may support connections to single phaseor multi-phase (e.g. three phase) systems. This embodiment can providefor increased flexibility in supplying power to utilization equipmentthat may or may not be co-located with one another, e.g., in the sameequipment rack. Thus, this embodiment may result in a reduced number ofconnections, reduce the space required for the power distribution systemand reduce the need for field wiring when supplying power to individualpieces of electrical equipment regardless of whether or not theelectrical equipment is rack mounted.

In various embodiments, the architecture provided by the bus barassembly 42 and the plug-in modules 20 allows for a scalable powerdistribution system that can more easily adapt to changes in theelectrical requirements of the facility (e.g., a data center) where itis installed. In particular, the architecture may allow a facility tosafely add new output circuits without the need for a power outage.

Further, in accordance with one embodiment, the architecture provides astandardized set of equipment ratings that can be employed in a widevariety of applications. As a result, manufacturers, equipment designersand facility operators can more easily and more economically supplypower distribution equipment, design scalable and adaptable powerdistribution systems, and maintain and expand power distributionsystems. That is, a very few “core” elements may be employed to supplypower to a wide variety of dynamic electrical loads.

The plug-in module 20 may include any of a variety of switching devices,however, where the plug-in module includes a circuit breaker, thecircuit breaker may have any of a wide range of continuous currentratings. This approach provides a system that is highly adaptable. Forexample, the plug-in module may be standardized for a specific maximumcontinuous current rating (e.g., 100 Amps). In one embodiment, thestandardized continuous current rating is the result of a selection ofthe plurality of contacts 58 and other conductors integral to theplug-in module, i.e., to provide hardware that is rated for a minimum of100 Amps. In addition, the sizing of the housing 22 may be selected suchthat it is sufficient to receive the largest molded case circuit breakerincluded in the available range of continuous current (e.g., 0-100Amps). According to one embodiment, the plug-in module is sized andadapted to receive circuit breakers configured for mounting on a DINrail, for example, circuit breakers with a continuous current rating offrom fractions of an Amp to 63 Amps. According to one embodiment, a DINrail is located within the housing 22 and the circuit breaker 34 ismounted on the rail. In one embodiment, the form factor across theentire range of current ratings is the same.

Various embodiments may integrate features of the plug-in module 20 intoa circuit breaker 34 (e.g., into the molded housing of a molded casecircuit breaker) such that the circuit breaker 34 can be installed inthe bus bar assembly 42 in the manner described herein for a plug-inmodule 20. For example, a circuit breaker may be equipped with aplurality of contacts 58 and the circuit breaker 34 and circuit breakerhousing may include any of or any combination of the guide element 36,the stress relief device 57, the connector 64, the handle 32, the latch33, the PCB 66, the processor 68, the memory 69 and the interlock 84. Inone embodiment, the housing 22 of the plug-in module is eliminated asdescribed here. In one embodiment, the circuit breaker 34 is sized andadapted to be directly installed in the bus bar assembly 42 without aseparate housing 22. Alternatively, some of the features described asbeing in the housing 22 may instead be included in a circuit breakerthat is installed in the housing 22 of the plug-in module 20.

The overall electrical ratings of the plug-in module 20 and the bus barassembly 42 may also be standardized to a very few ratings that eachmeet of a wide variety of applications. In some embodiments, thestandardized hardware is approved by one or more of UL, CSA and VDE. Inone embodiment, the standardized hardware includes a first set ofplug-in modules 20 and bus bar assemblies 42 rated for 208/120 Voltapplications, a second set rated for 415/240 Volt applications and athird set rated for 400/230 Volt applications. In each of the precedingembodiments, the bus bar assembly 42 may include a single standardizedcontinuous current rating of 400 Amps. As mentioned previously, such anapproach simplifies the manufacturing, distribution, selection andapplication of the power distribution equipment.

In various embodiments, the electrical isolation and overcurrentprotection may include any one of or any combination of circuitbreakers, trip elements, fuses and switchable contacts (e.g., switches).

Referring now to FIG. 11, a power distribution unit 1800 is illustratedin accordance with one embodiment. In the illustrated embodiment, thepower distribution unit 1800 includes a housing 1802, a plurality ofelectrical conductors 1803, and a power connection enclosure 1804. Insome embodiments, the housing includes an outer wall 1805 that providesa cavity 1808 therewithin. Further, in the illustrated embodiment, theouter wall 1805 defines an opening 1806 that in the illustratedembodiment extends linearly from a first end 1811 of the housing to asecond end 1813 of the housing. Further, although the first end 1811 ofthe housing is illustrated as being open, in other embodiments, thefirst end 1811 is closed.

According to the illustrated embodiment, the power connection enclosure1804 includes a connector 1807, for example, a male plug that isconfigured to connect to a connector included in the power cord thatsupplies electrical power to the power distribution unit 1800. Invarious embodiments, the power connection enclosure 1804 may includeconnector 1807 including any of a male plug, a female plug or any otherform of electrical connector known in the art. In another embodiment,the power connection enclosure 1804 may provide a connection point forpower cord where individual conductors are connected to the powerdistribution unit at a terminal strip or other similar style mechanicalconnection where, for example, a plug-style connector is not employed.In yet another embodiment, the power distribution unit 1800 is attachedto a first end of a power cord at the power connection enclosure 1804where the second end of the power cord is connected to a plug in module,for example, as illustrated in FIG. 15. In a further embodiment, thecord is pre-terminated at the plug-in module.

The invention is not restricted to any specific quantity of electricalconductors 1803. Accordingly, in one embodiment, the electricalconductors 1803 include a plurality of phase conductors supplied from amulti-phase power source. In some other embodiments, the electricalconductors 1803 include a single phase conductor. In addition, theelectrical conductors 1803 can include either or both of a neutralconductor and a ground conductor. Similarly, the power connectionenclosure 1804 can be configured to receive any of a ground conductor, aneutral conductor and any number of phase conductors.

In the embodiment illustrated in FIG. 11, each of a plurality of tapmodules 1810 can be removably attached to the power distribution unit byconnecting them at any user selected location between the first end ofthe housing 1811 and the second end 1813. The plurality of tap modules1810 can provide one or more electrical elements. For example, in theillustrated embodiment, a first tap module 1810A illustrates areceptacle outlet configured for direct connection to local utilizationequipment, a second tap module 1810B includes an integral lamp, and athird tap module 1810C includes an electrical cord 1814 which may alsoinclude a receptacle outlet 1816 located at the end of the electricalcord 1814 opposite a body of the tap module 1812.

Where the tap module 1810 includes a receptacle outlet, examples ofsingle phase outlets include NEMA types 5-15, L5-20 and L6-20, and IEC320 type C13 and C19. Examples of three phase receptacle outlets includeNEMA types L21-20, L14 and L15, and IEC 309. According to someembodiments, any of the preceding may be included at a distal end of apower cord 1814 included in the tap module 1810.

In accordance with some embodiments, the tap modules 1810 are connectedto the electrical conductors 1803 by inserting the tap module 1810 intothe cavity 1808 via the opening 1806 and rotating the tap module 1810 toengage one or more of the plurality of electrical conductors 1803. Inaccordance with one embodiment, the tap module is located in a firstrotational position when it is inserted within the cavity 1808 and thenrotated to a second rotational position (for example, a rotationalposition that is 90 degrees different) to complete the electricalconnection between the tap module 1810 and the power distribution unit1800.

Referring now to FIG. 12, an embodiment of the tap module 1810 isillustrated. In the illustrated embodiment, the tap module includes thebody 1812, a shaft 1818, a plurality of contacts 1826 and a lockingelement 1828. According to this embodiment, the shaft 1818 is sized andshaped to allow insertion of the shaft into the cavity 1808 via theopening 1806 while a diameter of the body 1812 is sufficiently large toprevent the body 1812 from being inserted through the opening 1806. Theshaft 1818 can include a first region 1820 having a first diameter andat least one second region 1822 having a second diameter. In accordancewith the illustrated embodiment, a single first region 1820 is includedon the shaft 1818 and a plurality of second regions each having thesecond diameter 1822 are included on the shaft 1818. Further, accordingto one embodiment, the first region is a region where a ground-conductorcontact included in the plurality of contacts 1826 is located while thesecond regions 1822 each include a region for a phase-conductor contact,respectively, included in the plurality of conductors 1826. In addition,a second region can be included to house a neutral-conductor contactincluded in the plurality of contacts 1826. Further, as illustrated,each of the first and second regions 1820, 1822 are separated fromadjacent regions on the shaft 1818 by slots 1824.

According to one embodiment, each of the body 1812 and the shaft 1818are manufactured from insulating material selected from any one of orany combination of thermoplastic or thermosetting materials, forexample, polycarbonates (PC), polyesters (PBT), polyphenal sulfide(PPS), etc. According to another embodiment, each of the body 1812 andthe shaft 1818 are manufactured from a bulk molding compound (BMC).

Each of the plurality of contacts 1826 includes a region exposed outsidethe shaft 1818 of which at least a part is uninsulated. FIG. 12illustrates each of the plurality of contacts 1826 in an embodimentwhere the exposed regions are entirely uninsulated, as one example. Inaddition to the exposed region, each of the contacts 1826 includes aportion that is located within the shaft 1818. It should be recognizedthat the necessary electrical connection between the plurality ofcontacts 1826 and the electrical element (i.e., receptacle outlet, lamp,cord, etc.) is completed within the shaft 1818 and/or body 1812.

Although the embodiment of FIG. 12 illustrates each of a plurality ofphase-conductor contacts included in the plurality of contacts 1826, thetap module 1810 can be configured to include fewer than three or morethan three phase conductors in some embodiments, for example, the tapmodule 1810 can include only a single phase conductor.

In accordance with one embodiment, the shaft 1818 is manufactured withthe first region 1820 and the second regions 1822 including an openingin each region by which a user can selectively add any of the contacts1826 required for their application by inserting the electricalconductor (also referred to as a conducting stab) within the opening.Thus, according to some embodiments, a user in the field can select theconfiguration of the tap module 1810 to improve and/or maintain abalanced loading of a multi-phase power source that supplies power tothe power distribution unit 1800. For example, a user may connect aplurality of tap modules to a multiphase power distribution unit 1800where each tap module 1810 includes a single phase receptacle outlet.According to one embodiment, the user can for a first tap module, inserta first contact in the opening configured for phase A; for a second tapmodule, insert a contact in the opening configured for phase B; and inthe third tap module, insert a contact in the opening configured forphase C. Assuming that the three receptacle outlets are connected toutilization equipment with similar power requirements, the powerdistribution module will draw a substantially balanced load. In oneembodiment, the openings configured to receive a conducting stab extendradially inward within the shaft 1818.

According to some embodiments, the locking member 1828 is a device thatis sized and shaped to engage a portion of the power distribution unit1800 to allow the tap module 1810 to be securely retained in place(absent a user's action). In accordance with the illustrated embodiment,the sliding device 1828 travels linearly (for example, in a direction oftravel illustrated by the arrow) adjacent the body 1812 to allow fullinsertion of the tap module 1810 within the housing 1802 while alsolocking the tap module in place when an electrical connection betweenthe tap module and the plurality of electrical conductors 1803 iscompleted. According to one embodiment, the locking member 1828 isspring biased in the direction of the shaft 1818 to allow the lockingmember to automatically secure the tap module in place when theelectrical connection is complete. For example, the locking member 1828may slide into the opening 1806 in the housing. To disconnect and removethe tap module 1801 from the housing 1802, the user manually withdrawsthe locking member from engagement with the opening 1806 to allowdisconnection and removal of the tap module 1810 from the housing 1802.

Other structure and other arrangements may be employed for the lockingmember 1828 in various embodiments. For example, the locking member 1828can be a device that requires the user to manually operate the lockingmember once the electrical connection is completed to secure the tapmodule 1810 in the connected position. Further, the locking member 1828can engage the housing 1802 in a different manner, for example, thelocking member can include a rotary latch.

Referring now to FIG. 13, the tap module 1810 of FIG. 12 is illustratedin accordance with one embodiment. The tap module 1810 includes thefirst region and the second region (each shown in phantom) havingdifferent diameters as mentioned above, and in addition, includes afirst planar side 1830 and a second planar side 1831 located on oppositesides of the shaft 1818. In the illustrated embodiment, the width of theshaft 1818 between a first planar surface 1830 and the second planarsurface 1831 is sized and configured to fit within the opening 1806. Forexample, the width of the shaft in the region between the planarsurfaces 1830, 1831 is sized to be slightly smaller than a dimension ofthe opening 1806.

In accordance with some embodiments, the shaft 1818 is fully insertedwithin the cavity 1808 before it is rotated into a connected position inwhich the electrical connection between the electrical conductors 1826and the plurality of electrical conductors 1803 is complete.Accordingly, in a first rotational position, the planar sides of theshaft 1818 align with the sides of the opening 1806 such that the shaft1818 can be inserted through the opening into the cavity 1808.

Referring now to FIG. 14, a connection of a tap module 1810 to a powerdistribution unit 1800 is illustrated in accordance with one embodiment.The power distribution unit 1800 includes the cavity 1808 provided bythe outer wall 1805 of the housing 1802. In addition, the linearlyarranged opening 1806 is defined by the outer wall 1805. In theillustrated embodiment, the cavity 1808 includes the plurality ofelectrical conductors 1803 and a plurality of insulating members 1832.According to the illustrated embodiment, each of the plurality ofelectrical conductors 1803 is formed in a generally U-shape and extendslinearly along a side of the cavity 1808 with the open part of the Uoriented perpendicular relative to the opening 1806. Insulating members1832 separate each of the electrical conductors 1803 from the adjacentelectrical conductor and/or the outer wall 1805 of the housing 1802.According to this embodiment, the slotted regions 1824 of the shaft arealigned with a corresponding insulating member 1832 when the tap moduleis fully inserted in a connected position within the housing 1802. Thefirst and second regions 1820 and 1822 are sized to fit between adjacentinsulating members 1832 when the tap module 1810 is rotated into theconnected position.

According to one embodiment, the insulating members 1832 aremanufactured via an extrusion process from any one or any combination ofpolycarbonates (PC), polyesters (PBT), polyphenal sulfide (PPS), etc.According to another embodiment, the insulating members 1832 aremanufactured as a post cut and formed from sheet thermoplastic orthermoset based material, for example, Nomex, Mylar, Polycarbonate, etc.

The tap module 1810 is inserted and placed in the fully connectedposition illustrated in FIG. 14 as follows: first, the tap module ispositioned such that the planar sides of the shaft 1818 align with theopening 1806. The tap module is then pushed inward such that the shaft1818 is fully inserted within the cavity 1808. As a result of this axialmotion, the locking member 1828 slides in an axial direction away fromthe housing 1802 as it is pressed against the housing. According to oneembodiment, the depth of the shaft 1818 is such that a surface of thebody 1812 about the shaft contacts the outer wall 1805 of the housingwhen the insertion is complete. In some embodiments, the tap module 1810is then rotated 90 degrees to rotate the conductors 1826 into engagementwith the corresponding electrical conductor 1803. The locking member1828 slides within the opening 1806 such that further rotation of thetap module is not possible when the tap module is properly oriented andthe 90 degree rotation is complete. If a user wishes to withdraw the tapmodule from the housing 1802, the user first withdraws the lockingelement 1828 from the opening 1806 to release the locking member andallow the tap module to be rotated to the disconnected position andwithdrawn, again with the planar sides 1830 and 1831 of the shaft 1818aligned with the opening 1806.

Referring again to FIG. 13, the first region 1820 provides a lobe thatassists the user in properly aligning the plurality of contacts 1826with the plurality of electrical conductors located within the housing1802 when the tap module is connected to the power distribution unit1800. For example, in one embodiment, the lobe provided by the firstregion 1820 has a diameter that is large enough (relative to thediameter of the second regions 1822) that the tap module 1810 cannot berotated in the fully connected position unless the shaft 1818 isinserted to the correct depth in the cavity to align the first region1820 with a region within the housing 1802 having a diametersufficiently large to receive the first region. In one example, thefirst region 1820 must be aligned with the region in the cavity wherethe ground conductor is located. It should be recognized that in variousembodiments the first region 1820 can correspond to the location of adifferent conductor provided that the cavity within which the shaft 1818is inserted is designed for that configuration. Thus, the first region1820 can correspond to the location of the neutral conductor or one ofthe phase conductors. Further, in some embodiments, a tap module 1810can be configured with two or more first regions 1820 such that properalignment is confirmed when each of the two regions is located in acorresponding region, respectively, within the cavity.

FIG. 15 provides a close-up view of the completed electrical connectionbetween the tap module 1810 and associated electrical conductors 1826and the plurality of electrical conductors 1803 of the powerdistribution unit 1800. Here, a further embodiment illustrates how adimensional difference between the first region 1820 and the secondregions 1822 is used to achieve proper alignment. The plurality ofelectrical conductors 1803 are disposed within the cavity 1806 providedby the outer wall 1805 of the housing. A distance D between a face 1836of the body 1812 and a longitudinal axis of a contact (for example, GND)located in the first region 1820 is established and the plurality ofelectrical conductors 1803 are oriented such that the contact in thefirst region aligns with the first region when the tap module is fullyinserted in the housing 1802. In the illustrated embodiment, the firstregion includes both a larger diameter and a greater width W than otherregions of the shaft 1818, to assist in properly aligning the tap modulefor completion of the electrical connections.

The above described embodiments can allow a user to easily add, removeand/or relocate a plurality of tap modules 1810 at any non-fixedlocation along the housing 1802 of the power distribution unit 1800. Thepreceding can be accomplished safely without need to de-energize thepower distribution unit 1800.

As described above, according to various embodiments, the contacts 1826are configured to be inserted and withdrawn from a corresponding firstor second region within slots provided in each of these regions.According to one embodiment, a user can connect a single phasereceptacle outlet included in a body 1812 of a tap module 1810 to aselected one of the available phases in a multi-phase power distributionunit while maintaining a ground and a neutral connection for thereceptacle outlet as well. Subsequent tap modules 1810 that areconnected to the housing 1802 can be connected to different phases tohelp maintain a balance load on the power system.

In accordance with various embodiments, the power distribution unit isconfigured as a rack mounted power distribution unit, similar to thegeneral configuration provided by the rack mounted power distributionunit illustrated in FIGS. 8 and 9. Thus, for example, in one embodiment,the housing 1802 and/or power connection enclosure 1807 can include oneor more flanges or other structure that allows power distribution unitto be installed in a standard electrical equipment rack. In someembodiments, the flange includes an opening for insertion of a screw orother fastener used to secure the housing 1802 to the electricalequipment rack.

According to these embodiments, the rack mounted power distribution unitincluding the housing 1802 allows for the connection of a plurality oftap modules at user selected locations within an electrical equipmentrack. This provides advantages including a reduction in the length ofelectrical cords used to connect the power distribution unit toutilization equipment located in the electrical equipment rack.

Although the tap modules 1810 illustrated herein include electricalcontacts 1826 which extend substantially perpendicular to thelongitudinal axis A of the tap module 1810, other orientations can beemployed in different embodiments. As one example, the electricalcontacts 1826 can be provided in the form of contact pads exposed at theexterior surface of the shaft 1818. According to this embodiment, theplurality of electrical conductors 1803 are oriented within the housing1802 to connect with the electrical contacts 1826. According to someembodiments, the electrical connection between the electrical contacts1826 and the plurality of electrical conductors 1803 can be completedusing only the linear insertion of the tap module 1810 within thehousing 1802. For example, the contacts 1826 can include conductingstabs that extend perpendicular to the shaft 1818. The relative positionof the electrical contacts 1826 can be offset relative to one anothersuch that each conductor slides into engagement with one of theplurality of electrical conductors as a result of the axial motionprovided to insert the tap module 1810 within the housing 1802.

According to some embodiments, the power distribution unit 1800 and thetap modules 1810 can include additional features to assist a user inanalyzing and managing the power system in which they are employed. Forexample, the tap modules can include integral voltage and/or currentsensing. Here, integral refers to the fact that the sensing devices areincluded in one or both of the shaft 1818 and the body 1812 of the tapmodule 1810. In addition to or in combination with the preceding, thepower distribution unit 1800 can include voltage and/or current sensing.According to one embodiment, the voltage and/or current sensing devicesare located in one or both of the power connection enclosure 1804 andthe housing 1802.

In another embodiment, the tap modules 1810 can include integral relays,for example, located in the body 1812, that operate to energize andde-energize the electrical element included in the tap module. Forexample, where the electrical element includes an electrical cord 1814and receptacle outlet 1816, the relay can be used to complete theelectrical connection between the electrical cord 1814 and one or moreof the electrical contacts 1826 at the instruction of a user. Thepreceding feature, for example, can be applied to advantage where theconnected load is a server by operating the relay to disconnect and thenreconnect the electrical connection to reboot the connected server.According to this embodiment the housing 1802 can include a controlpower bus for connection to the tap modules 1810 to provide controlpower for operation of the relays.

In further embodiments, the power distribution unit 1800 and/or tapmodules 1810 can include network communication hardware. For example,the housing 1802 can include a communication bus. The communication buscan be configured to connect to the tap modules 1810 when the tapmodules are inserted in the housing 1802 and placed in the fullyconnected position. According to this embodiment, the shaft 1818 caninclude one or more communication bus contacts. As some examples, thecommunication can include any of web enabled communication directly fromthe tap module 1810, Ethernet over power lines, and local CANBUScommunication between the tap modules and a web-card located in thepower distribution unit 1800. Further, a tap module 1810 can be providedwith a communication link as the integral electrical element. Accordingto this embodiment, a plurality of power distribution units 1800 (forexample, those located in adjacent equipment racks) can be connected toa common communication bus by linking one power distribution unit 1800to another by connecting communication links of the various powerdistribution units to one another via the tap modules 1810.

According to some embodiments, the tap modules 1810 or powerdistribution unit 1800 include overload protection. For example, thebody 1812 of the tap module can include a miniature circuit breaker orother device to provide overcurrent protection for load connected to thetap module 1810. Where overcurrent protection is included in the powerdistribution unit 100 a miniature circuit breaker or other overcurrentprotection device can be included in the power connection enclosure 1804which can be sized and configured to accommodate the device.

The apparatus and systems described herein may be employed to provide ascalable and flexible power distribution system for any of a widevariety of facilities including data centers and other commercial andindustrial facilities.

Having thus described several aspects of at least one embodiment of thisinvention, it is to be appreciated various alterations, modifications,and improvements will readily occur to those skilled in the art. Suchalterations, modifications, and improvements are intended to be part ofthis disclosure, and are intended to be within the spirit and scope ofthe invention. Accordingly, the foregoing description and drawings areby way of example only.

What is claimed is: 1.-20. (canceled)
 21. A rack mountable powerdistribution unit, comprising: a housing having a first end and a secondend, the housing including an outer wall defining a cavity within thehousing, the housing further including fastening elements configured toallow the housing to be mounted within an electrical equipment rack, theouter wall of the housing including an opening extending along a lengthof the outer wall of the housing between the first end and the secondend exposing the cavity; a plurality of electrical conductors locatedwithin the cavity and oriented within the cavity and extending along alength between the first end and the second end, wherein each of theplurality of electrical conductors includes an elongated slot, theelongated slot being generally U-shaped; and wherein each of theplurality of electrical conductors is separated from an adjacentelectrical conductor of the plurality of electrical conductors by aninsulating member.
 22. The system of claim 21, wherein the elongatedslot of each of a first group of the plurality of electrical conductorshas a first width, and wherein the elongated slot of each of a secondgroup of electrical conductors of the plurality of electrical conductorshas a second width different than the first width.
 23. The system ofclaim 21, wherein the plurality of electrical conductors includes aground conductor, a neutral conductor, and a single phase conductor. 24.A tap module for installing in a power distribution assembly, the tapmodule comprising: a body; a shaft coupled to the body including: afirst region having a first diameter, wherein the first region includesone or more locations for an electrical contact; and a second regionhaving a second diameter, wherein the second region includes one or morelocations for an electrical contact; at least one electrical contactincluded in the shaft and extending therefrom.
 25. The tap module ofclaim 24, wherein the shaft includes a first planar side and a secondplanar side parallel to the first planar side, and wherein the firstplanar side and the second planar side are located on opposite sides ofthe shaft.
 26. The tap module of claim 24, wherein the at least oneelectrical contact includes one or more of a phase-conductor contact, aneutral-conductor contact and a ground-conductor contact.
 27. The tapmodule of claim 24, wherein the at least one electrical contact isremovably coupled to the shaft.
 28. The tap module of claim 24, whereinthe at least one electrical contact is a plurality of electricalcontacts each having an exposed conductive surface.
 29. The tap moduleof 24, wherein the at least one electrical contact is a plurality ofelectrical contacts having an insulation layer disposed over a portionof conductive surface.
 30. The tap module of claim 24, furthercomprising network communication hardware within the body.
 31. The tapmodule of claim 30, wherein the network communication hardware includesa CANBUS controller.
 32. The tap module of claim 30, wherein the networkcommunication hardware includes an Ethernet controller.
 33. The tapmodule of claim 30, further comprising an electrical relay configured tobe controlled by signals from the network communication hardware. 34.The tap module of claim 24, further comprising a locking element locatedadjacent to the body.
 35. The tap module of claim 24, further comprisingat least one circuit breaker coupled to the at least one electricalcontact.
 36. A method of installing a rack mountable power distributionunit in a facility, the method comprising acts of: mounting the rackmountable power distribution unit in an electrical equipment enclosure,the rack mountable power distribution unit including a plurality ofelectrical contacts and being configured to receive a plurality ofelectrical tap modules at a plurality of non-fixed locations along alength of the rack mountable power distribution unit; obtaining aplurality of tap modules, each of the plurality of tap modules includinga plurality of electrical contacts; and installing at least one tapmodule of the plurality of tap modules in the rack mountable powerdistribution unit by sliding at least one tap module of the plurality oftap modules into the rack mountable power distribution unit such thateach of the plurality of electrical contacts of the at least one tapmodule of the plurality of tap modules is coupled to one or moreelectrical contacts in the rack mountable power distribution unit. 37.The method of claim 36, further comprising configuring the at least onetap module of the plurality of tap modules, before installing the atleast one tap module of the plurality of tap modules, by inserting oneor more electrical contacts into the at least one tap module of theplurality of tap modules.
 38. The method of claim 37, wherein the atleast one tap module of the plurality of tap modules includes a body,and wherein the act of inserting one or more electrical contacts intothe at least one tap module of the plurality of tap modules includesremovably coupling each of the one or more electrical contacts to aphase conductor included in the body.
 39. The method of claim 37,wherein the at least one tap module of the plurality of tap modulesincludes a body, and wherein the act of inserting one or more electricalcontacts into the at least one tap module of the plurality of tapmodules includes removably coupling each of the one or more electricalcontacts to a circuit breaker included in the body.
 40. The method ofclaim 37, wherein the at least one tap module of the plurality of tapmodules includes a body, and wherein the act of inserting or one moreelectrical contacts into the at least one tap module of the plurality oftap modules includes removably coupling each of the one or moreelectrical contacts to a communication bus included in the body.